work on the high resolution structure of phosphoglucomutase by X-ray diffraction analysis will be continued by (a) conducting crystal binding studies with substrate and substrate analogs and (b) initiating attempts to obtain isomorphous crystals containing heavy metal ions. Sequence studies of the enzyme also will be initiated. Preliminary structural studies with glucose bisphosphate synthase also will be conducted. Experiments to show that a conformational change in the enzyme accompanies the catalytic transformation of phospho-enzyme glucose bisphosphate complexes will be continued by using the inactive Li ion complex of the enzyme, as well as by using the substrate analogs, 6-deoxyglucose-1-P and 1-deoxyglucose-6-P. The use of endogenous serum phosphoglucomutase as a metal ion indicator for free Zn2ion also will be investigated.